438 PTERIDOPHYTES (FERN PLANTS) 
tively. The gametophytes are small, green, ribbon-like bodies and 
lie flat on the surface of the substratum. The male gametophyte 
is the smaller and is one cell in thickness. It bears the antheridia 
on the tips of the lobes or on the margin. The female gametophyte 
Fig. 391. — The gametophytes of Equisetum arvense. A, female gameto- 
phyte, showing one archegonium (ar) (X about 20). B, male gametophyte 
with four antheridia shown (2%) (X about 40). 
forms a cushion, a number of cells in thickness, on the upper sur- 
face of which the archegonia are borne. 
The multiciliate sperms, after being set free from neighboring 
male gametophytes, swim to the archegonia and down their necks 
to the eggs. The fertilized egg begins to develop immediately 
and continues until a new sporophyte is formed, and the life cycle 
is thus completed. 
Lycopodiales (Club Mosses) 
About one-eighth of the living Pteridophytes are Club Mosses. 
They are commonly divided into four groups — Lycopodium 
Phylloglossum, Selaginella, and Isoetes— but a study of the 
Lycopodiums and the SelaginelJlas will serve to give a general 
notion of the Club Mosses. 
The Club Mosses, although not Mosses at all, get their name 
from their Moss-like stem and their club-shaped appearance due 
to the large terminal strobili which some have. 
Lycopodium. — There are several hundred species of Lycopo- 
diums, and they are widely distributed, occurring in both hemi- 
spheres and from the torrid to the frigid zones. They prefer 
shady places and some are aquatic. 
